A Saudi police officer was killed and six others wounded when a patrol came under attack in the town of Awamiya in eastern Saudi Arabia on Sunday morning, the interior ministry said.
Several policemen have been killed in the Shi'ite Muslim town since May when authorities began tearing down the old part of the town to deny suspected militants a place to hide.
At least five people were killed over two days last week when security forces began an operation to flush out suspected militants in Awamiya, in Qatif province, part of the oil-producing region, according to local activists and a relative of one of the deceased.
On Sunday, the police patrol came under a "terrorist attack using an exploding projectile" near the walled part of Awamiya known as al-Musawara, the interior ministry said in a statement carried by state news agency SPA.
The six wounded were in stable condition in hospital, it said.
Residents say shooting by security forces has forced many locals and expatriate workers to flee the town.
The area has seen unrest and occasional armed attacks on security forces since the 2011 "Arab spring" protests. Residents of Awamiya complain they are marginalised by the Sunni-led Saudi government, something Riyadh denies.
Authorities say they intend to replace the dilapidated 200-year-old al-Musawara with a modern district.